Trithiophosphoric acid ester as a soil pesticide

ABSTRACT

A trithiophosphoric acid ester of the formula; ##STR1## wherein R 1  is methyl or ethyl group, which is useful as a soil pesticidal composition for pests in soil.

The present invention relates to a trithiophosphoric acid ester of theformula (hereinafter referred to as present compound): ##STR2## whereinR₁ is methyl or ethyl group, its production and soil pesticidalcompositions containing it as an active ingredient.

That some kinds of trithiophosphoric acid ester, for example, O-ethylS,S-di-sec-butyl trithiophosphate, O-ethyl S,S-di-iso-butyltrithiophosphate, etc., can be used as an active ingredient forinsecticides and nematocides, is described in U.S. Pat. No. 3,839,510,and also that, for example, O-ethyl S,S-di-n-butyl dithiolphosphate,etc., similarly can be used as an active ingredient for insecticides andnematocides, is described in Japanese Patent Publication No. 29847/1969.But, it may not always be said that these compounds are alwayssatisfactory as an active ingredient for soil pesticides.

While, the present compound has a high controlling activity againstpests living in soil and doing damage to paddy rice, vegetables, flowersand ornamental plants, lawn grasses, fruit trees, tea, mulberry and thelike, and besides said compound gives no such phytotoxicity as to becomea problem to these plants.

The present compound, therefore, can be used as an active ingredient forsoil pesticidal composition used for paddy field, plowland, orchard,pasture, tea garden, mulberry farm and the like.

The soil pest includes for example pests of Diabrotica genus such aswestern corn rootworm (Diabrotica virgifera Le Conte), northern cornrootworm (Diabrotica longicornis Say), southern corn rootworm(Diabrotica undecimpunctata howardi Barber), etc., pests of Anomalagenus such as cupreous chafer (Anomala cuprea Hope), soybean beetle(Anomala rufocuprea Motschulsky), cherry chafer (Anomala daimianaHarlod), striated chafer (Anomala testaceips Motschulsky), etc., pestsof Popillia genus such as Japanese beetle (Popillia japonica Newman),etc., pests of Aulacophora genus such as cucurbit leaf beetle(Aulacophora femoralis Motschulsky), etc., pests of Phyllotreta genussuch as striped cabbage flea beetle (Phyllotreta vittata Fabricius),etc., pests of Melanotus genus such as sweetpotato wireworm (Melanotuscaudex Lewis), etc., pests of Agriotes genus such as barley wireworm(Agriotes fuscicollis Miwa), etc., pests of Hylemya genus such as onionmaggot (Hylemya antiqua Meigen), turnip maggot (Hylemya floralisFallen), seed-corn maggot (Hylemya platura Meigen), etc., pests ofAgrotis genus such as common cutworm (Agrotis segetum Denis etSchiffermuller), black cutworm (Agrotis ipsilon Hufnagel), etc., pestsof Gryllotalpa genus such as African mole cricket (Gryllotalpa africanaPalisot de Beauvois), etc., pests of Lissorhoptrus genus such asricewater weevil (Lissorhoptrus oryzophilus Kuschel), etc., pests ofPratylenchus genus such as Cobb root-lesion nematode (Pratylenchuspenetrans Cobb), walnut root-lesion nematode (Pratylenchus vulnus Allenet Jensen), coffee root-lesion nematode (Pratylenchus coffeaeZimmermann), etc., pests of Heterodera genus such as soybean cystnamatode (Heterodera glycines Ichinohe), etc., pests of Meloidogynegenus such as northern root-knot nematode (Meloidogyne hapla Chitwood),cotton root-knot nematode (Meloidogyne incognita var. acrita Chitwood),Javanese root-knot nematode (Meloidogyne javanica Treub), peanutroot-knot nematode (Meloidogyne arenaria Neal), etc., pests ofAphelenchoides genus such as rice white-tip nematode (Aphelenchoidesbesseyi Christie) and the like.

The present compound can be produced by reacting a dithiolphosphoricacid ester of the formula: ##STR3## wherein R₁ is as defined above, witha 1,3-dithia-2,4-diphosphethane-2,4-disulfide of the formula: ##STR4##wherein R₂ is lower alkyl, phenyl or thiophene group or phenyl groupsubstituted with halogen atom, lower alkyl or lower alkoxyl group.

The reaction is generally carried out in a solvent not disturbing itsprogress such as hydrocarbons (e.g. n-hexane, benzene, toluene, xylene),ethers (e.g. tetrahydrofuran, dioxane), halogenated hydrocarbons (e.g.chlorobenzene, dichlorobenzene) and the like.

As to the amount of reagent used for reaction,1,3-dithia-2,4-diphosphethane-2,4-disulfide (III) of at least 0.5 moleis used based on 1 mole of a dithiolphosphoric acid ester (II). Thereaction temperature is about 80° C. to about 120° C., and the reactiontime is about 30 minutes to about 10 hours.

After completion of the reaction, the reaction product is purified bychromatography, distillation, etc., if necessary.

Also, the present compound can be produced by reacting O-alkylS,S-di-tert-butyl phosphite of the formula: ##STR5## wherein R₁ is asdefined above, with sulfur or thiophosphoryl trichloride.

O-Alkyl S,S-di-tert-butyl phosphite (IV), a material, can be produced,for example, by the following method: Phosphorus trichloride is reactedwith tert-butylmercaptan of 2 equivalents based on it in a solventdescribed later at a reaction temperature of from about -20° C. to about20° C. using, generally, a tertialy amine (e.g. triethylamine, pyridine,N,N-dimethylaniline) as a dehydrochlorinating agent, or phosphorustrichloride is reacted with tert-butylmercaptan at a reactiontemperature of from about 20° C. to about 90° C. for several to ten andseveral hours. After reaction, the formed, S,S-di-tert-butylchlorophosphite may or may not be isolated from the reaction solution ormay be purified by distillation, etc., if necessary. Thereafter, theS,S-di-tert-butyl chlorophosphite, either as the above reaction solutionas such when it has not been isolated or in re-dissolution in the abovesolvent when it has been isolated, is reacted with an alcohol oralcoholate of not less than one equivalent based on it at a reactiontemperature of from about 0° C. to about 50° C. The foregoing solventincludes for example hydrocarbons (e.g. hexane, benzene, toluene),ketones (e.g. acetone, methyl isobutyl ketone), halogenated hydrocarbons(e.g. chlorobenzene, carbon tetrachloride, chloroform), acetonitrile andthe like.

When an alcohol is used, it is a common practice to use a tertiary amine(e.g. triethylamine, pyridine, N,N-dimethylaniline) as adehydrochlorinating agent.

After completion of the reaction, the resulting product may be used assuch for the subsequent reaction, but if necessary, it may be isolatedand purified by after-treatment such as washing with water, etc.

As described above, the present compound can also be produced asfollows: To O-alkyl S,S-di-tert-butyl phosphite (IV) thus obtained isadded sulfur or thiophosphoryl trichloride of 1 to 3 equivalents basedthereon or a mixture of the both, reaction is carried out at 70° C. to120° C. and after reaction, the common after-treatment is applied toobtain the desired product. In this case, O-alkyl S,S-di-tert-butylphosphite is used either as the above reaction solution as such when ithas not been isolated or in re-dissolution in the above solvent orwithout the solvent when it has been isolated.

After completion of the reaction, the reaction product is purified bycolumn chromatography, distillation, etc. if necessary.

Production examples for the present compound will be shown.

PRODUCTION EXAMPLE 1

To a solution of 2.7 g of O-ethyl S,S-di-tert-butyl phosphorodithiolatein 50 ml of toluene was added 2.1 g of2,4-bis(4-methoxyphenyl)-1,3-dithia-2,4-diphosphethane-2,4-disulfide,and the mixture was refluxed for 1 hour with stirring. Toluene wasremoved by evaporation under reduced pressure, and a pale yellow oilyproduct obtained as a residue was purified by column chromatography onsilica gel to obtain 1.8 g of a colorless and oily O-ethylS,S-di-tert-butyl phosphorotrithioate [Present compound (1)].

    n.sub.D.sup.28 1.5368

PRODUCTION EXAMPLE 2

6.9 Grams of phosphorus trichloride and 9.7 g of tert-butylmercaptanwere dissolved in 150 ml of hexane, and a solution of 11.0 g oftriethylamine in 10 ml of hexane was added dropwise thereto withstirring while maintaining the inner temperature of the reactionsolution at 0° C. or less. After completion of the addition, thereaction solution was aged with stirring until its inner temperaturereached 20° C. Thereafter, a mixed solution of 1.8 g of methanol and 5.5g of triethylamine was added dropwise with stirring while maintainingthe inner temperature of the reaction solution at 25° C. or less. Aftercompletion of the addition, the reaction solution was aged with stirringat 25° C. for 30 minutes. Thereafter, the reaction solution was washedwith 20 ml of 5% HCl and then with water while maintaining its innertemperature at 5° C. or less. Hexane was removed by evaporation from theorganic layer under reduced pressure to quantitatively obtain an oilyproduct as a residue. After dissolving this product in 50 ml of toluene,1.9 g of sulfur and 9.0 g of thiophosphoryl trichloride were added andthe mixture was stirred at 105° C. for 30 minutes. After completion ofthe reaction, toluene and thiophosphoryl trichloride were removed underreduced pressure, hexane was added to the residue, and the mixture wasthen washed with 5% aqueous sodium carbonate solution and then withwater. Hexane was removed by evaporation under reduced pressure, and theresidue obtained was purified by column chromatography on silica gel toobtain 9.7 g of a colorless and oily O-methyl S,S-di-tert-butylphosphorotrithioate [Present compound (2)].

    n.sub.D.sup.30 1.5449

When the present compounds are used as an active ingredient for soilpesticidal compositions, they are generally formulated into oil sprays,emulsifiable concentrates, wettable powders, granules, dusts, aerosols,etc. by mixing with an inert carrier such as solid, liquid or gaseouscarrier and if necessary, adding auxiliaries for formulation such assurface active agents and others.

These compositions contain 0.1 to 99.9% by weight, preferably 1 to 80%by weight of the present compound as an active ingredient.

The solid carrier includes for example fine powders or granules of clays(e.g. kaolin clay, attapulgite clay, diatomaceous earth, synthetichydrated silicon dioxide, Fubasami clay, bentonite, terra abla), talcs,other inorganic minerals (e.g. sericite, quartz powder, sulfur powder,activated carbon, calcium carbonate, hydrated silica), chemicalfertilizers (e.g. ammonium sulfate, ammonium phosphate, ammoniumnitrate, urea, ammonium chloride) and the like. The liquid carrierincludes for example water, alcohols (e.g. methanol, ethanol), ketones(e.g. acetone, methyl ethyl ketone), aromatic hydrocarbons (e.g.benzene, toluene, xylene, ethylbenzene, methylnaphthalene), aliphatichydrocarbons (e.g. n-hexane, cyclohexane, kerosene, petroleum ether),esters (e.g. ethyl acetate, butyl acetate), nitriles (e.g. acetonitrile,isobutyronitrile), ethers (e.g. dioxane, diisopropyl ether), acid amides(e.g. dimethylformamide, dimethylacetamide), halogenated hydrocarbons(e.g. dichloroethane, trichloroethylene, carbon tetrachloride) and thelike. The gaseous carrier, i.e. propellant, includes for example freongas, butane gas, carbon dioxide gas and the like.

The surface active agent includes for example alkyl sulfates,alkylarylsulfonates, alkylsulfonates, alkyl aryl ethers and theirpolyoxyethylenized products, polyethylene glycol ethers, polyhydricalcohol esters, sugar alcohol derivatives and the like.

The fixing agent and dispersing agent include for example casein,gelatin, polysaccharides (e.g. starch powder, gum arabic, cellulosederivatives, alginic acid), lignin derivatives, bentonite, saccharides,synthetic water-soluble high polymers (e.g. polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acids) and the like. The stabilizer includesfor example PAP (isopropyl acid phosphate), BHT(2,6-di-tert-butyl-4-methylphenol), BHA (mixture of2-tert-butyl-4-methoxyphenol and 3-tert-butyl-4-methoxyphenol),vegetable oils, mineral oils, surface active agents, fatty acids andtheir esters, and the like.

These compositions may be used, as such or as aqueous dilute liquors, byspraying or scattering onto soil surface and if necessary, mixing withthe soil after spraying or scattering, or drenching soil. Sometimes,they may be used in foliar spraying. Also, they may be used in mixturewith other insecticides, acaricides, nematocides, fungicides, seeddisinfectants, fertilizers or soil improvers, or may be used at the sametime together with these chemicals without mixing.

Formulation examples for the present compound will be shown. Hereupon,all parts are by weight.

FORMULATION EXAMPLE 1 Emulsifiable Concentrate

40 Parts of the present compound (1) or (2) is dissolved in 50 parts ofxylene, and 10 parts of Sorpol SM-200, an emulsifier, (mixture ofpolyoxyethylene alkylaryl ether, etc., and dodecylbenzenesulfonic acid;a registered trade mark of Toho Kagaku Co.) is added thereto. Themixture is then well mixed by stirring to obtain a 40% emulsifiableconcentrate of each compound.

FORMULATION EXAMPLE 2 Wettable Powder

To 40 parts of the present compound (1) or (2) is added 5 parts ofSorpol SM-200, and after thorough mixing, 20 parts of Carplex #80(synthetic hydrated silicon dioxide fine powder; a registered trade markof Shionogi Seiyaku Co.) and 35 parts of 300-mesh diatomaceous earth areadded thereto. The mixture is then mixed by stirring on a juice mixer toobtain a 40% wettable powder of each compound.

FORMULATION EXAMPLE 3 Granule

To 5 parts of the present compound (1) or (2) are added 5 parts ofToyolignin CT (ligninsulfonate; a registered trade mark of Toyo SpinningCo.) and 90 parts of GSM clay (quartz powder; a registered trade mark ofZieklite Mining Co.), and the mixture is well mixed by stirring on amortar. Thereafter, to the mixture is added water corresponding to 10%thereof, and the resulting mixture is further stirred, granulated on agranulator and air-dried to obtain a 5% granule of each compound.

FORMULATION EXAMPLE 4 Dust

5 Parts of the present compound (1) or (2) is dissolved in 20 parts ofacetone, and 3 parts of Carplex #80, 0.3 part of PAP and 91.7 parts of300-mesh talc are added thereto. The resulting mixture is mixed bystirring on a juice mixer, and acetone is removed by evaporation toobtain a 5% dust of each compound.

FORMULATION EXAMPLE 5 Oil Spray

20 Parts of the present compound (1) or (2) is dissolved in 80 parts ofkerosene to obtain a 20% oil spray of each compound.

FORMULATION EXAMPLE 6 Granule

15 Parts of the present compound (1) or (2) is dissolved in 10 parts ofdiethylene glycol, and the resulting solution is well mixed with 75parts of Attapulgus clay 25/50 mesh (attapulgite clay produced byEngelhard Co.) while spraying the solution onto the stirred clay. A 15%granule of each compound is thus obtained.

When the present compounds are used as an active ingredient for soilpesticidal compositions, the dosage rate is generally 10 to 1000 g/10ares, preferably 50 to 500 g/10 ares, and the application concentrationis 0.01 to 30% when the emulsifiable concentrate, wettable powder or thelike is diluted with water.

These dosage rate and application concentration vary with the form ofpreparation, application time, application scene, application method,kind of soil pest, degree of damage and the like, so that they may beincreased or decreased independently of the foregoing ranges.

The controlling activity on soil pests of the present compounds will beshown with reference to the following test examples. Every test examplewas carried out according to a three-replication test. Of testcompounds, the present compounds are shown by Compound No. in ProductionExamples and compounds used as a control are shown by Compound symbol inTable 1.

                  TABLE 1                                                         ______________________________________                                        Com-                                                                          pound                                                                         symbol                                                                              Chemical structure Remark                                               ______________________________________                                        (A)                                                                                  ##STR6##          Ethoprophos                                          (B)                                                                                  ##STR7##          Compound described in U.S. Pat. No. 3839510.         (C)                                                                                  ##STR8##          Compound described in Japanese                                                Patent Publication No. 29847/1969.                   (D)                                                                                  ##STR9##          Compound described in U.S. Pat.                      ______________________________________                                                                 No. 3839510.                                     

TEST EXAMPLE 1

The emulsifiable concentrate of each test compound formulated accordingto Formulation Example 1 was diluted with water, and 5 ml of theresulting aqueous dilute liquor was mixed with 50 g of soil (16 mesh) tomake the concentration of active ingredient in soil 0.5 ppm. The soilwas then placed in a polyethylene cup of 5.6 cm in diameter and 5.8 cmhigh, and two pieces of corn having roots of 2 to 3 cm long wereplanted. At the same time, ten third instar larvae of southern cornrootworm (Diabrotica undecimpunctata howardi Barber) were liberated inthe cup. Two days after liberation, the number of the dead and alive ofthe larvae was examined to obtain mortality (%). The result is shown inTable 2.

                  TABLE 2                                                         ______________________________________                                        Test compound  Mortality (%)                                                  ______________________________________                                        (1)            100                                                            (2)            100                                                            (A)            50                                                             (B)            0                                                              (C)            0                                                              (D)            0                                                              No treatment   0                                                              ______________________________________                                    

TEST EXAMPLE 2

The emulsifiable concentrate of each test compound formulated accordingto Formulation Example 1 was diluted with water, and 20 ml of theresulting aqueous dilute liquor was mixed with 500 g of soil to make theconcentration of active ingredient in soil 1 ppm. The soil was thenplaced in a polyethylene cup of 10 cm in diameter and 8 cm high, and apiece of cut carrot was buried as bait. At the same time, four thirdinstar larvae of cupreous chafer (Anomala cuprea Hope) were liberated inthe cup. Seven days after liberation, the number of the dead and aliveof the larvae was examined to obtain mortality (%). The result is shownin Table 3.

                  TABLE 3                                                         ______________________________________                                        Test compound  Mortality (%)                                                  ______________________________________                                        (1)             90                                                            (2)            100                                                            (A)             60                                                            No treatment    0                                                             ______________________________________                                    

What is claimed is:
 1. A trithiophosphoric acid ester of the formula:##STR10## wherein R₁ is methyl or ethyl group.
 2. The trithiophosphoricacid ester according to claim 1, wherein R₁ is methyl group.
 3. Thetrithiophosphoric acid ester according to claim 1, wherein R₁ is ethylgroup.
 4. A method for controlling soil pests which comprises applying apesticidally effective amount of the trithiophosphoric acid esteraccording to claim 1 to the soil pests.
 5. A soil pesticidal compositionwhich comprises a pesticidally effective amount of the trithiophosphoricacid ester according to claim 1, as an active ingredient and an inertcarrier.